Animate the bubble bar for the first bubble

This change animates the bubble bar for the first bubble.
When we're in home -- the bubble bar bounces in and stays visible
When we're in app -- the bubble bar bounces in, then animates to
the stashed handle.
When the bubble bar auto expands, we currently animate the bubble
bar already expanded. In the future we'll time the expansion
until after the bubble bar settles in.

Demo: http://recall/-/bJtug1HhvXkkeA4MQvIaiP/hIGwtb3YKyCT9Ke9adZNgY

Flag: ACONFIG com.android.wm.shell.enable_bubble_bar DEVELOPMENT
Bug: 339066271
Test: atest BubbleBarViewAnimatorTest
Change-Id: I80ce55676b72a50bab23623e0b5c1e602690682f

quickstep/src/com/android/launcher3/taskbar/bubbles/BubbleBarViewController.java

@@ -406,10 +406,21 @@ public class BubbleBarViewController {
                 return;
             }
 
+            if (!(b instanceof BubbleBarBubble bubble)) {
+                return;
+            }
+
             boolean isInApp = mTaskbarStashController.isInApp();
+            // if this is the first bubble, animate to the initial state. one bubble is the overflow
+            // so check for at most 2 children.
+            if (mBarView.getChildCount() <= 2) {
+                mBubbleBarViewAnimator.animateToInitialState(bubble, isInApp, isExpanding);
+                return;
+            }
+
             // only animate the new bubble if we're in an app and not auto expanding
-            if (b instanceof BubbleBarBubble && isInApp && !isExpanding && !isExpanded()) {
-                mBubbleBarViewAnimator.animateBubbleInForStashed((BubbleBarBubble) b);
+            if (isInApp && !isExpanding && !isExpanded()) {
+                mBubbleBarViewAnimator.animateBubbleInForStashed(bubble);
             }
         } else {
             Log.w(TAG, "addBubble, bubble was null!");